Measurement method, and terminal
A method can measure the size of an object using a terminal having two cameras. The method includes obtaining, by a terminal using a first camera, a first image that includes a to-be-measured object, and obtaining, using a second camera, a second image that includes the to-be-measured object, where the first camera and the second camera are disposed in a same plane. The method also includes comparing locations of the to-be-measured object in the first image and in the second image, so as to obtain a total location offset of the to-be-measured object. Additionally, the method includes receiving a measurement point selection instruction entered by a user based on the first image, and calculating a distance between selected measurement points according to the total location offset, a distance between a center of the first camera and a center of the second camera, and a focal length of the first camera.
1. A method, comprising:
obtaining, by a terminal using a first camera, a first image that comprises a to-be-measured object;
obtaining, by the terminal using a second camera, a second image that comprises the to-be-measured object, wherein the first camera and the second camera are disposed in a same plane;
receiving, by the terminal, a measurement point selection instruction entered by a user based on the first image;
determining, by the terminal, selected measurement points in accordance with the measurement point selection instruction;
comparing, by the terminal, a first location of the to-be-measured object in the first image and a second location of the to-be-measured object in the second image, to obtain a total location offset of the to-be-measured object, wherein the total location offset is determined based on a sum of a first location offset of the first location in the first image and a second location offset of the first location in the second image, the first location corresponding to one of the selected measurement points; and
calculating, by the terminal, a distance between the selected measurement points according to the total location offset, according to a distance between a center of the first camera and a center of the second camera, and according to a focal length of the first camera.
2. The method according to claim 1 , wherein the method further comprises:
compressing imaging data of the first image and the total location offset as an image file;
storing the imaging data of the first image and the total location offset that are compressed as the image file, after comparing the first location of the to-be-measured object in the first image and the second location of the to-be-measured object in the second image;
parsing the image file, to obtain the imaging data of the first image and the total location offset; and
decoding the imaging data, to display the first image on a screen of the terminal, before receiving the measurement point selection instruction.
3. The method according to claim 1 , wherein the method further comprises:
displaying, on a screen of the terminal, a distance result obtained by calculation, after calculating the distance between the selected measurement points.
4. The method according to claim 1 , wherein the method further comprises:
notifying, by voice, the user, of a distance result obtained by calculation, after calculating the distance between the selected measurement points.
5. The method according to claim 1 , wherein comparing the first location of the to-be-measured object in the first image and the second location of the to-be-measured object in the second image is performed using the formula:
D=X 1 +X 2 ,
wherein D is the total location offset of the to-be-measured object, X 1 is the first location offset, and X 2 is the second location offset.
6. The method according to claim 1 , wherein calculating the distance between the selected measurement points is performed using the formula:
L
=
D
1
*
(
X
p
D
p
-
X
q
D
q
)
2
+
(
Y
p
D
p
-
Y
q
D
q
)
2
+
(
H
1
D
p
-
H
1
D
q
)
2
,
wherein L is the distance between the selected measurement points, (X p , Y p ) are coordinates of a measurement point p in the first image, D p is a total location offset of the measurement point p, (X q , Y q ) are coordinates of a measurement point q in the first image, D q is a total location offset of the measurement point q; and H 1 =h 1 /a, wherein h 1 is the focal length of the first camera and a is a size constant of a single pixel, wherein D 1 is the distance between the center of the first camera and the center of the second camera, and wherein one of the D p or D q is the total location offset.
7. The method according to claim 1 , wherein the method further comprises:
calculating a vertical distance from the to-be-measured object to a line connecting the center of the first camera and the center of the second camera by using the formula:
Z=H 1* D 1 /( X 1 +X 2 ),
wherein Z is the vertical distance from the to-be-measured object to the line connecting the center of the first camera and the center of the second camera, H 1 =h 1 /a, wherein h 1 is the focal length of the first camera and a is a size constant of a single pixel, D 1 is the distance between the center of the first camera and the center of the second camera, X 1 is the first location offset, and X 2 is the second location offset.
8. The method according to claim 1 , wherein the method comprises:
calculating a distance between two measurement points in response to the user selecting the two measurement points; and
successively calculating distances between every two neighboring measurement points according to a selection order, in response to the user selecting more than two measurement points.
9. A terminal, comprising:
an input device comprising a first camera and a second camera, wherein the first camera and the second camera are disposed in a same plane, and wherein the first camera and the second camera are configured to obtain images of a to-be-measured object;
an output device;
a processor coupled to the input device and to the output device; and
a non-transitory computer readable storage medium storing a program for execution by the processor, the program including instructions to:
obtain, using the first camera, a first image that comprises the to-be-measured object;
obtain, using the second camera, a second image that comprises the to-be-measured object;
receive a measurement point selection instruction entered by a user based on the first image;
determine selected measurement points in accordance with the measurement point selection instruction;
compare a first location of the to-be-measured object in the first image and a second location of the to-be-measured object in the second image, to obtain a total location offset of the to-be-measured object, wherein the total location offset is determined based on a sum of a first location offset of the first location in the first image and a second location offset of the first location in the second image, the first location corresponding to one of the selected measurement points; and
calculate a distance between the selected measurement points according to the total location offset, according to a distance between a center of the first camera and a center of the second camera, and according to a focal length of the first camera.
10. The terminal according to claim 9 , wherein the instructions further comprise instructions to:
compress imaging data of the first image and the total location offset as an image file, after obtaining the total location offset of the to-be-measured object;
store the imaging data of the first image and the total location offset that are compressed as the image file;
parse the image file, to obtain the imaging data of the first image and the total location offset; and
decode the imaging data, to display the first image on a screen of the terminal, before receiving the measurement point selection instruction entered by the user.
11. The terminal according to claim 9 , wherein the output device is a screen, and wherein the screen is configured to:
display a distance result obtained by calculation, after calculating the distance between the selected measurement points.
12. The terminal according to claim 9 , wherein the output device is configured to:
notify, by voice, the user, of a distance result obtained by calculation, after calculating the distance between the selected measurement points.
13. The terminal according to claim 9 , wherein the instructions to compare the first location of the to-be-measured object in the first image and the second location of the to-be-measured object in the second image using the formula:
D=X 1 +X 2 ,
wherein D is the total location offset of the to-be-measured object, X 1 is the first location offset, and X 2 is the second location offset.
14. The terminal according to claim 9 , wherein the instructions further comprise instructions to:
calculate the distance between the selected measurement points by using the formula:
L
=
D
1
*
(
X
p
D
p
-
X
q
D
q
)
2
+
(
Y
p
D
p
-
Y
q
D
q
)
2
+
(
H
1
D
p
-
H
1
D
q
)
2
,
wherein L is the distance between the selected measurement points, (X p , Y p ) are coordinates of a measurement point p in the first image, D p is a total location offset of the measurement point p, (X q , Y q ) are coordinates of a measurement point q in the first image, D q is a total location offset of the measurement point q, and H 1 =h 1 /a, wherein h 1 is the focal length of the first camera and a is a size constant of a single pixel, and wherein D 1 is the distance between the center of the first camera and the center of the second camera, and wherein one of the D p or D q is the total location offset.
15. The terminal according to claim 9 , wherein the instructions further comprise instructions to:
calculate a vertical distance from the to-be-measured object to a line connecting the center of the first camera and the center of the second camera using the formula:
Z=H 1* D 1 /( X 1 +X 2 ),
wherein Z is the vertical distance from the to-be-measured object to the line connecting the center of the first camera and the center of the second camera, H 1 =h 1 /a, wherein h 1 is the focal length of the first camera and a is a size constant of a single pixel, D 1 is the distance between the center of the first camera and the center of the second camera, X 1 is the first location offset, and X 2 is the second location offset.
16. The terminal according to claim 9 , wherein the instructions to calculate the distance between the selected measurement points comprise instructions to:
calculate a distance between two measurement points, in response to the user selecting the two measurement points; and
successively calculate distances between every two neighboring measurement points according to a selection order, in response to a user selecting more than two measurement points.
17. A non-transitory computer readable medium storing a program for execution by a processor of a terminal, the program including instructions for:
obtaining, using a first camera, a first image that comprises a to-be-measured object;
obtaining, using a second camera, a second image that comprises the to-be-measured object, wherein the first camera and the second camera are disposed in a same plane;
receiving a measurement point selection instruction entered by a user based on the first image;
determining selected measurement points in accordance with the measurement point selection instruction;
comparing a first location of the to-be-measured object in the first image and a second location of the to-be-measured object in the second image, to obtain a total location offset of the to-be-measured object, wherein the total location offset is determined based on a sum of a first location offset of the first location in the first image and a second location offset of the first location in the second image, the first location corresponding to one of the selected measurement points; and
calculating a distance between the selected measurement points according to the total location offset, according to a distance between a center of the first camera and a center of the second camera, and according to a focal length of the first camera.